Preface

**Section 4**

**Section 5**

**II**

Guided Waves in Free Space **99**

**Chapter 7 101**

**Chapter 8 119**

Physics of Waveguiding **143**

**Chapter 9 145**

**Chapter 10 167**

Radiation Fluxes Waveguide-Resonance Phenomenon Discovered

Characteristics of Radiation of a round Waveguide through a Flat

Study of Refraction Effects for Propagation over Terrain *by Vladimir Schejbal, Ondrej Fiser and Vadim Zavodny*

Mode Interferences of VLF Waves in the Presence

in Result of X-Ray Nanosize Beam Formation Study

of an Anisotropic Terrestrial Waveguide *by Ting Ting Gu and Hong Lei Xu*

*by Egorov Evgenii Vladimirovich and Egorov Vladimir Konstantinovich*

Homogeneous Heat Shield *by Viktor F. Mikhailov*

Optical and microwave waveguides have attracted much research interest in both science and industry. The number of applications for their use is rapidly growing. This book presents a collection of recent advances in the broad field of waveguide technology. It covers the current progress and latest breakthroughs in emergent applications in photonics and microwave engineering.

The book includes ten contributions on recent developments in waveguide technologies including theory, simulation, and fabrication of novel waveguide concepts.

The editor Patrick Steglich provides a brief overview of important developments in the field of waveguide technologies in photonics and microwave engineering as well as current trends and perspectives.

Ran Gao and JianSen Ye provide a review on optical fiber sensors based on antiresonant reflecting optical waveguides, including the single layer, double layers, double resonators, and hybrid mechanism.

Helena Cristina Vasconcelos focuses on developing coatings for use as waveguides for integrated optics and photonics. Here, the waveguides are based on sol-gel materials.

Trung-Thanh Le and Duy-Tien Le present their results on graphene-silicon multimode waveguides. There results show that such waveguides can provide a very high free spectral range (FSR) and capability of controlling the critical coupling.

Hedi Sakli and Wyssem Fathallah present an extension of the rigorous analysis of the propagation of electromagnetic waves in transverse magnetic (TM) and transverse electric (TE) modes in a metallic circular waveguide partially filled with anisotropic metamaterial.

Shotaro Ishino, Satoshi Denno, Narumi Yashiro, and Seiichi Suzuki report on the development of a waveguide-type leaky-wave antenna and the development of a wireless LAN environment in a tunnel.

Vladimir Schejbal, Ondrej Fiser, and Vadim Zavodny investigate the radio-wave propagation above irregular ground, including the troposphere, using physical optics computation.

Ting Ting Gu, Hong Lei Xu, and Kai Li illustrate the disturbing nature during sunrise and sunset for Very Low Frequency (VLF) waves with periodic variations in amplitudes interfered by multi-modes over long propagation paths.

Egorov Evgenii Vladimirovich, and Egorov Vladimir Konstantinovich discuss waveguide-resonance mechanism relevation forerunner of characteristic X-ray radiation flux propagation and the technology of the planar air extended slit clearance preparation.

Viktor F. Mikhailov provides a solution for obtaining an analytical description of the radiation characteristics of a circular waveguide closed by a flat homogeneous dielectric plate.

We thank all authors for their contributions.

Finally, we express a great deal of thanks to the editing staff of IntechOpen, particularly Ms. Dolores Kuzelj, for all their efforts.

Sincerely,

Section 1

Introduction

**Dr. Patrick Steglich** IHP – Leibniz-Institute for Innovative Microelectronics, Frankfurt, Germany

> Technical University of Applied Sciences Wildau, Wildau, Germany

Section 1 Introduction

**3**

**Chapter 1**

*Patrick Steglich*

**1. Introduction**

develop future innovations.

the visible and infrared light spectra.

such as gas sensor can be addressed.

different types of waveguides based on silicon.

Introductory Chapter:

Microwave Engineering

losing power while it propagates inside the waveguide.

Electromagnetic Propagation and

Waves can propagate as spherical waves in open space. In this case, the power of the wave decreases with the distance from the source as the square of the distance. In contrast, a waveguide can confine the propagating wave in such a way that the wave propagates only in one dimension. Assuming ideal conditions, the wave is not

Waveguides play a major role for applications in communications and sensing technologies. The theoretical understanding and practical investments are crucial to

In photonics, two major types of waveguides can be distinguished, namely optical fibers and integrated waveguides. Waveguides in photonics operate typically in

Optical fibers are used for data transmission, as fiber lasers, for flexible transmission of laser radiation or for lighting, for sensor applications or decoration purposes [1]. The main application of optical fibers, however, is their use in telecommunication systems, making our daily life easier by a fast internet connection [2]. Other important technical applications of optical fibers are lasers [3], interferometers [4, 5], amplifier [6], and sensors [7]. The latter is important since it allows the detection of magnetic fields [8], humidity [9], temperature [10], and biological molecules [11, 12]. Massive research investments in the field of optical fibers [13–15] have led to novel applications. One important example is the use of optical for endoscopic applications [16, 17]. Also the fiber core has been modified (**Figure 1**), so that novel applications

Integrated waveguides confine light in submicrometer structures on chip. Such waveguide structures are made either by doping the substrate material or by structuring it with etching procedures. Mostly, such waveguides are formed by patterning semiconductor materials like silicon, which is known as photonic integrated circuit technology [18]. The dimension of those waveguides in single mode operation is typically about 220 nm in width and 500 nm in height. **Figure 2** shows three

The main applications are electro-optical modulators in telecommunications [19] and integrated sensors [20, 21] for point-of-care-diagnostics, environmental monitoring, or food analysis [22, 23]. A relatively novel approach is the silicon-organic hybrid technology [24–26]. Here, the silicon-based waveguide is covered with organic materials [27–29] leading to highly energy-efficient modulators [30] with large 3-dB

Waveguides in Photonics and
